The major goals of the proposed project are the characterization of functional properties and quantitative stimulus-response relationships of single neurons of two brain stem tracts, both having their cells of origin in the main cuneate nucleus, the cuneothalamic tract and the exteroceptive component of the cuneocerebellar tract. Microelectrodes will be used to record neural activity in tract cell bodies and fibers in response to controlled mechanical stimulation of the glabrous skin of the raccoon forepaw. Both anesthetized, and decerebrate, preparations will be used, and identification of the neurons as tract cells will be achieved by antidromic stimulation techniques. Specific parameters to be examined include modality and adaptive properties, absolute thresholds and receptive field areas, as well as effects of controlled mechanical stimulus velocity, indentation depth, and force on both dynamic and static discharage rate and pattern. It is hoped that results will contribute to the understanding of the differential contributions of spinocerebral and spinocerebellar systems to active touch and sensorimotor integration. In addition, the results should provide information relevant to diagnosis and localization of brain stem and spinal cord damage, brought about by injury or disease.